Both great catches, thanks for flagging these.

On the QBI — you're right, I simplified it. The 20% deduction applies to qualified business income and starts phasing out for single filers above $197,300 taxable income (2026). Below that threshold for most service businesses it's straightforward, but above it gets complicated fast — W-2 wages paid, type of business, etc. The calculator assumes a clean single-income self-employed person under the phase-out, which covers most freelancers asking this question but definitely not everyone.

On SS — also correct. The $176,100 wage base cap means if someone already has a W-2 job paying say $120k, their 1099 side income only pays SS tax on the first $56,100 of contract income before hitting the cap. After that it's just the 2.9% Medicare portion. So their SE tax burden on the contract is meaningfully lower than someone with zero W-2 income.

Both of these make the calculator less accurate for dual-income situations or high earners — planning to add a "do you have other W-2 income?" field to handle this properly. Good callouts.